Fluorescent lamps are a conventional type of lighting device which are gas charged devices that provide illumination as a result of atomic excitation of low-pressure gas, such as mercury, within a lamp envelope. The excitation of the mercury vapor atoms is provided by means of a pair of arc electrodes mounted within the lamp. In order to properly excite the mercury vapor atoms, the lamp is ignited and operated at a relatively high voltage, and at a relatively constant current. The excited atoms emit invisible ultraviolet radiation. The invisible ultraviolet radiation in turn excites a fluorescent material, e.g., phosphor, that is deposited on an inside surface of the fluorescent lamp envelope, thus converting the invisible ultraviolet radiation to visible light. The fluorescent coating material is selected to emit visible radiation over a wide spectrum of colors and intensities.
Fluorescent lamps have substantial advantages over conventional incandescent lamps. In particular, the fluorescent lamps are substantially more efficient and typically use 80 to 90% less electrical power than an equivalent light for output incandescent lamps.
Recently, compact fluorescent tubes have become available which have light outputs equivalent to 100 to 200 watt incandescent bulbs.